1. Field of the Invention
The present invention relates to an image pickup lens for forcing a subject image on an image pickup element such as a CCD sensor or a CMOS sensor, and relates to an image pickup lens suitable for a video camera, a monitoring camera, a digital still camera, and the like and an image pickup apparatus including the same.
2. Description of the Related Art
Of image pickup optical systems used in image pickup apparatuses such as digital video cameras in recent years, a video camera with a wide angle of field over 160° is increasingly popular. Such a video easier a with a wide angle of field is regained to be compact and have high optical performance.
Many wide angle lenses have conventionally been proposed for use in the above-mentioned video camera, monitoring camera, and the like. For example, Japanese Patent Application Laid-Open No. 2005-221920 and Japanese Patent Application Laid-Open No. 2004-145256 each propose a wide angle lens including 6 lenses in 5 lens units.
The image pickup lenses described in Japanese Patent Application Laid-open No. 2005-221920 and Japanese Patent Application Laid-open No. 2004-145256 achieve an angle of field of 160° or more, but have a problem that the total lone length is long as the distance from a lens surface on the most object side to an image plane is about 10 times the focal length. These wide angle lenses have the angle widened by inducing large negative distortion. That is, an optical image is formed by compressing a subject on the image plane. However, since lateral chromatic aberration is reflected on the image plane without being compressed, there is also a problem that the influence of lateral chromatic aberration is more noticeable when a larger amount of distortion is induced for angle widening.